Ceramic matrix composites have been identified as candidate materials for components in the hot-section of jet engines due to their high temperature capability, low weight, and low coefficient of thermal expansion. In some instances these components are manufactured by laying up stacked 2D cloth or using 3D laminates to form a fiber preform, depositing a fiber-matrix interphase coating and rigidizing the fiber preform through chemical vapor infiltration (CVI), infiltrating the rigidized fiber preform with a ceramic slurry to form an impregnated fiber preform, and melt infiltrating the impregnated fiber preform with molten silicon to render the composite nearly fully dense.
The densified composite may have a surface topography that mimics the woven architecture of the fiber preform, instead of a smooth surface as desired to avoid an adverse impact on aerodynamic performance. A possible remedy is to apply a slurry-based surface coating to a partially processed composite to improve the surface uniformity, particularly after slurry infiltration and prior to melt infiltration. This can prove difficult, however, due to the tendency of the fiber preform to wick solvent from the slurry away from the surface. This wicking effect may cause localized consolidation which can allow the woven texture to persist throughout the surface coating.